There has been known an in-vehicle navigation device that acquires traffic information (VICS data) on traffic conditions such as traffic accidents and traffic jams from a Vehicle Information Communication System (VICS) and superimposes indications representing the traffic conditions such as the traffic accidents and the traffic jams on map information displayed on a display screen of a display unit to notify a user of the traffic conditions. In many cases, when a traffic jam occurs, drivers who are avoiding the traffic-jam might cause a secondary traffic jam on the roads around the original traffic-jam. The traffic condition notified based on the VICS data represents the current condition, and therefore the drivers avoiding the traffic jam based on the notified current traffic condition might be caught in the secondary traffic jam. Thus, there is a demand for improved navigation devices that can navigate drivers to travel more smoothly.
Meanwhile, as an in-vehicle navigation device, there has been known an arrangement that predicts and notifies current and future traffic conditions with the use of statistical traffic-jam information data obtained by statistically processing the past traffic-jam information (see, for example, Patent Document 1). The in-vehicle navigation device disclosed in Patent document 1 notifies statistical traffic-jam information according to time factors such as time and day of the week based on the statistical traffic-jam information data by superimposing the information on map information in various expressions corresponding to traffic-jam conditions. With the notified time and day of the week, users can predict current and possible future traffic jams.
[Patent Document 1] Japanese Laid-Open Patent Publication No. Hei 9-113290 (right column of page 3 to left column of page 7).